Astronomers Say This Planet With 3 Suns is the Weirdest Exoplanet Ever Discovered

Friday, 08 July 2016 - 6:53AM
Astronomy
Friday, 08 July 2016 - 6:53AM
Astronomers Say This Planet With 3 Suns is the Weirdest Exoplanet Ever Discovered
Tatooine-style planets that orbit a dual star-system are a dime a dozen these days, but planets that orbit three stars are a much rarer breed. In fact, up until now only one such exoplanet had been discovered. But as a new paper in the Journal Science reveals, the European Southern Observatory's (ESO) Very Large Telescope has uncovered another exoplanet with three suns, but this one probably shouldn't even exist.

Located some 320 light years away from Earth, planet HD 131399Ab is unlike anything we've ever seen before. The first triple-star system exoplanet to be discovered actually only orbited one of its stars closely, barely being influenced by the other two stars in its neighborhood. Planet HD 131399Ab, however, defies all logic by being influenced by all three of its host stars. 

Opening quote
"I'd venture to say this is the weirdest orbit of any exoplanet we've ever found," Kevin Wagner, lead author on the study told Gizmodo. "We know of no other planet in a configuration like this."
Closing quote

The study found that planet HD 131399Ab's primary orbit is around a young type-A star, taking a whopping 550 years to complete one cycle. However, off in the distance, two other stars have an influence on the giant planet, making its orbit erratic and and ever-changing.

Opening quote
"The planet is about a third of a way out [between star A, and the B/C pair]," Wagner continued. "All of the stars have a lot of gravitational influence on the planet, meaning it has a very irregular orbit that's constantly evolving and changing."
Closing quote

Wagner and his team are still working to study the planet's orbit, but it's not yet clear if this irregular configuration will allow the HD 131399Ab any kind of long term future. It's wobbly, ever-changing orbit could eventually place HD 131399Ab on a collision path with another object, or it could simply have found itself a nice little niche in this peculiar star system. 

HD 131399Ab is four times as massive as Jupiter, and with an orbit that's twice as far as Pluto is from our sun, it's also one of the coldest planets ever to be directly imaged. This unfamiliar climate hasn't stopped Wagner from imagining what this rare triple-star system would look like from the planet's surface, though.

Opening quote
"I like to start thinking about it from when the planet is opposite all three stars. When they aren't eclipsing, you'd see three suns in the sky. As the planet progresses in its orbit, the stars will start to grow apart, to the point where the setting of one coincides with the rising of another."
Closing quote

HD 131399Ab's discovery isn't just a landmark achievement because of its weirdness, though. The planet's existence means that triple-star systems like this might not be as rare as they were previously thought. While astronomers have discovered many dual-star systems in the vastness of space, they hadn't even really attempted to look for triple configurations, purely because they simply didn't think that there were that many out there. HD 131399Ab might just change the way astronomers go about their business.
Science
Space
Astronomy

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